So starting with I believe the NPM 12.2 series of releases, anytime I run a Config Wizard on the primary poller, any of my WPM playback locations that are polled by an additional poller stop playing back.
Once I go into each Location and Edit, and then choose the primary poller as the polling engine for the playback location, the transactions show back up as green (previously unknown). Then I can set the locations back to the additional poller they were originally assigned to.
Not sure if anyone else has seen this behavior.